This program of PET research contains three projects and the associated core facilities necessary to conduct these studies. The projects represent a continuation of our studies in patients with schizophrenia, epilepsy and Parkinson's disease. A common thread among these projects will be the study of the alterations in the cerebral response to activation tasks. This will not only provide important information concerning the potential reorganization of these processes in the brain in disease states, but will aid in our understanding of the organization and processing of such information in the normal brain. In Project 10, PET activation studies will be used to examine brain function and search for neural substrates of schizophrenia. The study is designed to evaluate the regional specificity of abnormalities in brain activation response to cognitive challenge tasks. In addition, the pattern of resting glucose metabolism will be related to the course of illness. Project 11 will study brain injury and recovery of function in humans with temporal lobe epilepsy (TLE). It will assess cognitive organization, including language and memory, consequent to the initial injury causing the epilepsy. The project will then evaluate cognitive reorganization following anterior temporal lobectomy (ATL) to determine which areas of the brain participate in recovery, and examine pre-operative organization and reorganization after ATL in light of age at the time of first brain injury. Project 12 will address the controversy surrounding the presence and nature of cognitive and language deficits in patients with Parkinson's disease (PD). The proposed study will characterize the prevalence and nature of cognitive deficits in these patients, and relate cognitive performance to cerebral function with positron emission tomography (PET).